Work will continue to proceed in four areas the coming year: (1) Further characterization of the cardiovascular effects of ionophores, including an accurate and complete picture of their underlying mechanism of action and evaluation of their potential therapeutic application to man and animals; (2) evaluation of the environmental hazard to man of the widespread use of ionophores as feed additives for food producing animals including improvement of radiochemical assays we are developing for the rapid and convenient estimation of ionophore levels in meat at the marketplace and in other environmental sources; (3) modulation of the complexation behavior of ionophores by naturally occurring lipid components with regard to its significance on the assay we are developing and how this interaction affects ionophore-mediated transport in isolated membranes and biological membrane systems; (4) physico-chemical studies of the molecular basis of ionophore-cation complexation by a variety of spectrometric techniques including circular dichroism, nuclear magnetic resonance, fluorescence etc.